The validation and implementation of the Dutch version of the Quality of Life questionnaire for patients with primary hyperparathyroidism (PHPQoL)

Primary hyperparathyroidism (PHPT) is an endocrine disease characterized by
elevated levels of parathyroid hormone (PTH) most of the time caused by a
parathyroid tumor or hyperplasia. As a result of the hyperparathyroidism,
patients are exposed to increased calcium levels. Poor control of hypercalcemia
can increase the risk of mortality, due to its negative effect on the
cardiovascular-, gastrointestinal-, and nervous system, as well as on the
kidneys, bones and muscles. However, most patients with hyperparathyroidism
remain asymptomatic with calcium levels <2.9 mmol/L and absence of kidney or
bone disorders. Currently these patients are not treated with surgery, since
strict criteria for surgery are maintained including calcium levels >2.9
mmol/L, presence of renal stones and osteoporosis.
Besides physical symptoms, PHPT has been associated with psychopathology,
neuropsychological problems and impairments in health-related quality of life
(HRQoL), which significantly improves after surgical treatment. However, the
benefit of surgery in terms of improving HRQoL in asymptomatic patients or in
patients with minor symptoms remains inconclusive.
For the assessment of HRQoL it is usually recommended to use both a generic
questionnaire and a disease-specific questionnaire, in order to examine general
aspects of HRQoL, as well as specific HRQoL aspects relevant for a particular
disease]. Adequate assessment of HRQoL is important for the evaluation of
treatment and individual treatment choices in patient care. HRQoL assessment is
also used in clinical trails or to evaluate HRQoL in patient populations [9].
Recently, a disease-specific HRQoL questionnaire for PHPT has been developed
and validated i.e., the PHPQoL]. Currently, this questionnaire is only
available in Spanish and English.The aim of the present research protocol is to
translate the PHPQoL into Dutch, and validate it in a Dutch cohort of patients
with PHPT. When the Dutch PHPQoL is found to be valid and reliable, it will be
used as a standard quality check in our coordinated care trajectory (CCT) HPT.
The availability of a Dutch version of the PHPQoL will optimize treatment for
patients with (a) symptomatic PHPT.

Primary objective: To validate a disease-specific HRQoL questionnaire i.e., the
PHPQoL, in a Dutch cohort.
Secondary objective: To determine the effect of surgery, medical treatment or
conservative treatment in patients with PHPT within our CCT.

A prospective cohort study including consecutive patients of the CCT PHPT.
Translation of the PHPQoL will be performed according to international
standards by using the forward-backward method and debriefing interviews with
patients.
Patients visiting the outpatient clinic of the department of Endocrinology and
Endocrine Surgery will be invited to fill out the Dutch PHPQoL and two other
HRQoL measures (i.e., SF-36, EQ-5D) at time of diagnosis and 3 months after
treatment or in case of conservative treatment at the first follow-up visit.

The PHPQoL is a 16-item questionnaire containing disease-specific HRQoL items.
The other generic HRQoL questionnaires (i.e., SF-6D, EQ-5D) consist of 6 items
and 5 items respectively. We consider the patient perceived burden minimal.